Cemented hard metal (or sintered hard metal) is used in cutting tools for chipforming machining of metal materials, in high-strained tools and in wear parts of all kinds. Generally, the cemented hard metal contains hard materials (or hard principles), usually consisting mainly of tungsten carbide with small amounts of titanium carbide, tantalum carbide, niobium carbide, hafnium carbide and vanadium carbide in an amount of 70-97% by weight and 3-30% by weight of so-called binder metals, usually being cobalt, nickel, iron or their alloys.
Tungsten carbide has many properties which make it especially suited for use as a hard material in cemented hard metals. It has, for example, great hot hardness and high strength. Furthermore, the wettability between WC and binder metals such as Co is excellent. These properties are particularly related to the abovementioned hexagonal structure. Many attempts have been made to substitute other hard materials for the relatively expensive tungsten carbide, but this has either failed or has given rise to products with changed or impaired properties. Attempts to substitute for the W in the tungsten carbide, either partly or completely, with the related metal Mo has in most cases, demanded special procedures which have turned out to be completely uneconomical, or has given rise to hard materials with unsatisfactory stability, particularly at high temperatures.
However, as described in related U.S. Patent Application Ser. No. 872,926, filed Jan. 27, 1978, it has been found that a molybdenum-tungsten-carbonitride (Mo,W)(C,N), having the same type of structure as WC and a better thermal stability than the corresponding molybdenum-tungsten-carbide (Mo,W)C, can be obtained by means of relatively simple and economical methods of manufacture. The molybdenum-tungsten-carbonitride normally has a nitrogen content of 0.05-0.5 percent by weight, but may have a nitrogen content of up to about 1.2-1.5 percent by weight at high concentrations of molybdenum.